1. Field of the Invention
This invention relates to a disc recording and/or reproducing apparatus for recording and/or reproducing information signals using a disc cartridge comprised of a disc housed within a cartridge main body.
2. Description of the Prior Art
There has been proposed a recording/reproducing apparatus for recording and/or reproducing information signals using a disc cartridge comprised of a recording disc, such as an optical disc or a magneto-optical disc, housed within a cartridge main body.
The recording/reproducing apparatus, disclosed in, for example, U.S. Pat. No. 3,845,502, includes a loading unit for transporting the disc cartridge to a predetermined loading position, a rotating driving unit for holding the recording disc of the disc cartridge in its loading position and rotationally driving the disc, and a head device for writing and/or reading the information signals on or from the recording disc.
The loading unit is adapted for moving a cartridge holder by a cam or the like, which cartridge holder is adapted for holding the disc cartridge. The cartridge holder is adapted for holding the disc cartridge in parallel with the chassis. The loading unit shifts the cartridge main body, held by the cartridge holder, in a direction parallel to the major surface of the recording disc, that is, parallel to the chassis. When the recording disc is at a position directly above the rotating driving unit, the loading unit shifts the disc cartridge in a direction normal to the chassis and in a direction approaching the chassis.
The recording disc housed within the disc cartridge, thus moved in the direction approaching the chassis, is held by the rotating driving unit mounted on the chassis.
The head device is mounted on the chassis for facing the major surface, that is the signal recording surface, of the recording disc rotated by the rotating driving unit. The head device is supported for being moved radially across the inner and outer peripheries of the disc. With the recording disc being rotated and the head device being moved radially of the recording disc, the information signals may be recorded and/or read on or from substantially the entire signal recording surface of the recording disc.
Meanwhile, if the recording disc is an optical disc or a magneto-optical disc, an optical pickup device is used as the head device. This optical pickup device includes an optical lens driving device for effecting focusing and tracking servo control operations for servo controlling the light flux radiated onto the recording disc against deviations or offsets caused by revolutions of the recording disc brought about by the rotating driving unit. This object lens driving device supports the object lens for converging the light flux emanated from a light source of the optical pickup device by a supporting member which is formed of a flexible material for supporting the object lens for movement along an optical axis of the object lens and in a direction normal thereto, that is in a focusing direction and in a tracking direction. The object lens driving device also includes electromagnetic driving means for moving the lens in these two directions, These electromagnetic driving means include a coil mounted on a lens bobbin holding the object lens and supplied with a driving current and a magnetic circuit adapted for causing the magnetic flux to pass through the coil.
In the above-described disc recording/reproducing apparatus, the disc cartridge is positioned along its height and in an in-plane direction parallel to the chassis, with the chassis as a reference, while the recording disc is positioned along its height and in its in-plane direction by the rotating driving unit. That is, the disc cartridge is positioned in the vertical and horizontal directions with respect to the chassis by being engaged with or set on the distal end of a positioning pin mounted upright on the chassis. On the other hand, the recording disc is set and positioned on a disc table of the rotating driving unit. The disc table is substantially in the form of a disk mounted on a driving shaft of a spindle motor adapted for rotationally driving the recording disc. The spindle motor is mounted on the chassis.
In the disc recording/reproducing apparatus, it is difficult to maintain a predetermined relative position between the cartridge main body of the disc cartridge in the loaded position and the recording disc. Since the cartridge main body is positioned along its height and in the horizontal direction with respect to the chassis by the positioning pin provided on the chassis, while the recording disc is separately positioned by the disc table of the rotating driving unit, it is difficult to adjust the two positioning means, that is the positioning pin and the disc table, with respect to each other. It is because the recording disc holding position is subject to an error which is the sum total of errors of the spindle motor and the disc table and dimensional errors produced when mounting the spindle motor and the disc table. For accurately positioning and holding the recording disc so that the recording disc is not abutted against the inner wall of the cartridge main body during disc rotation, the spindle motor and the disc table need to be mounted with high accuracy, thus complicating the production.
On the other hand, for positioning the cartridge main body of the disc cartridge separately from the recording disc, it is necessary to provide a positioning member, such as the positioning pin, thus increasing the number of component parts.
Besides, in the disc recording/reproducing apparatus, provided with the above-described loading unit, since the loading unit is complicated in construction, it is difficult to simplify and reduce the size of the structure, as well as to simplify the production.
In addition, the above-described disc recording/reproducing apparatus, since both the rotating driving unit and the optical pickup device are mounted on the chassis, a loop of resonant vibrations tends to be produced between the rotating driving unit and the pickup device. That is, in the present disc recording/reproducing apparatus, vibrations induced in the disc driving rotating device and those induced in the optical pickup device tend to be propagated through the chassis to interfere with each other to produce resonant vibrations not only of the driving rotating unit and the optical pickup device but also of the chassis. If such resonant vibrations are produced, the optical pickup device cannot be operated satisfactorily, so that the information signals cannot be recorded or reproduced satisfactorily. Although means such as changing the chassis shape have been used for preventing these resonant vibrations, it has been difficult to prevent these resonant vibrations completely.